33S Prof. Bischof on the Temperature of 



tliat of ihe air at the mouth of the retort 64>°.175. The thermo- 

 meter did not rise to 65°. 75 until some drops of water had distill- 

 ed over. At this point it remained for several minutes, whilst 

 the mineral water continued to boil, and it was not until aque- 

 ous vapours were visible that it rose by degrees as high as 212°. 



It is, therefore, quite evident that the carbonic acid gas had a 

 very small share in the raising of the thermometer, but rather 

 that the aqueous vapours produced this effect. 



I repeated this experiment, and luted a receiver filled with 

 distilled water air-tight into the neck of the retort. The volume 

 of the mineral water in the retort was to that of the distilled 

 water in the receiver as 1 to 0.77. As the mineral water was 

 over-saturated with carbonic acid, the water in the receiver could 

 still, after subtracting the quantity of carbonic acid left in the 

 mineral water, absorb nearly sufficient to saturate itself. The 

 acidulous water was heated by degrees to 187°.25,* and kept for 

 a long time at that temperature. The total increase of tempe- 

 rature, however, only amounted to 0°.675; which is just the 

 same as was observed by Henry, 



I again varied the foregoing experiment by causing a stream 

 of carbonic acid gas, which I evolved from an acidulous water 

 by boiling, to pass through a column of water 18 inches high. 

 The volume of the column of water was equal to 1, that of the 

 water from which the gas was evolved equal to 3.37, that of the 

 space in the retort unoccupied by the mineral water equal to 

 6.63, and the volume of the gas contained in the water may be 

 taken at least as equal to 4. As the boiling was kept up so 

 long as gas continued to rise, about 10.63 volumes of carbonic 

 acid gas and atmospheric air must have passed through the co- 

 lumn of water. The temperature of the air during the experi- 

 ment was 60°.125, that of the column of water at the commence- 

 ment 5^°,B ; and, until the water in the retort began to boil, the 

 highest temperature it acquired was 61°.8. But afterwards, 

 when great quantities of aqueous vapour accompanied the car- 

 bonic acid gas, it rose by degrees to 180^.5 ; and it is evident 

 that these vapours must have also had some share in the increase 

 of 7°.2 observed before the mineral water began to boil. 



■ The cement with which the thermometer was luted into the tubulus of 

 the retort would not allow of a stronger heat. 



